The final trailer for the third season of Netflix's Stranger Things is remarkably revealing for a series built on mystery (OK, and nostalgia). The biggest revelation, perhaps, is confirmation of a long-percolating fan theory about the loathsome Billy Hargrove.

However, there are also suggestions of a deep, enduring connection between the Upside Down and Will and Eleven, a relationship between Hopper and Joyce (sure to please viewers), and a secret scientific base hidden beneath the product-placement goldmine of Starcourt Mall. But that's only the beginning.

THERE’S A PARTICLE COLLIDER UNDER THE MALL?

For instance, the location of the (possible) particle collider seems to be in the mall’s basement, which may explain why a Hawkins-wide blackout appears to begin at that location.

THE ABANDONED FACTORY IS AN UPSIDE-DOWN MAGNET

We also get more shots of the abandoned Brimborn Steel Works, which attracts a lot of rats, not to mention Billy Hargrove. It was first teased last month in a Season 3 poster.

ELEVEN'S BEACH VISION

That’s another red flag: This beach isn't even real, because Hawkins, Indiana, isn't anywhere near the shore. So, unless Eleven takes another road trip, there’s no way that an actual beach appears in Season 3.

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It's instead probably a vision of the Upside Down, and given the Lovecraftian undertones that permeate Stranger Things, it wouldn’t be too far-fetched to take the sea as a metaphor for the inscrutable universe from which the Deep Ones/the Mind Flayers emerge.

MIKE'S BASEMENT INVASION

Immediately after Eleven’s vision, Mike’s basement seems to be attacked by the Mind Flayer; in this shot we can see Eleven trying to hold its tentacle heads while Lucas, Will, Mike and Max huddle in the corners.

THE MIND FLAYER WILL POSSESS BILLY

The trailer seems pretty straightforward: At some point, Billy will enter the abandoned factory, the Mind Flayer will establish a connection with him, his eyes will develop black tendrils, and a flayed monstrosity will appear in front of him (or maybe will take over him; that part is unclear).

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THE MIND FLAYER (OR MAYBE BILLY) WILL ATTACK NANCY

Here, we can see Nancy fighting for her life under the same skinless creature that was in front of Billy in the factory, or possibly Billy himself, transformed.

ENRICHED URANIUM IN SCOOP AHOY!

Dustin and Steve find a strange green substance in a tube, similar to the pop idea of what enriched uranium looks like. This same substance later appears close to the particle collider, which again points at its location underneath the mall.

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A TALL & CREEPY STRANGER

This goon appears three times: in the forest, next to a sheriff car in disrepair; fighting Hopper with a machine gun; and one standing next to the Hadron collider, looking suspiciously chill with whomever is trying to open a portal to the Upside Down.

BUT ALL IS GOOD BECAUSE JOYCE & HOPPER WILL HOLD HANDS

On a lighter note, we clearly see Sheriff Hopper and Joyce Byers holding hands. It would be fantastic if these two end up together, although between her trailer and his creepy cabin the woods they might want to consider renting a condo.

AT ONE POINT, THERE WILL BE FOUR TEAMS

By the time the mall gets destroyed, the fighter planes start arriving and the Fun Fair is canceled due to an otherworldly invasion, our heroes will be grouped as follows:

Adults Team: Hopper, Joyce and Brauman. That Brauman is here might signal a connection to the Russian conspiracy theories of Season 2 (“The Russians have taken over Hawkins!”).

Kids Team 1: Will, Jonathan, Nancy and Lucas, at the mall, crouching behind a beat-up car

Kids Team 2: Max, Eleven and Mike, in the mall hiding Jurassic Park-style from the monster

Kids Team 3: Steve, Robin, Dustin and Erica, will escape the mall and reach a moonlit field equipped with a makeshift antenna. Here, they will watch the black helicopters fly toward Hawkins, and they will try to communicate with their trapped friends through a walkie-talkie.

Too bad that said walkie-talkie gets requisitioned by Comrade Mind Flayer.

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WILL CAN STILL FEEL THE MIND FLAYER

Will scratches his neck whenever something strange is about to happen. Is he completely free of the Upside Down's influence? Is he a human alarm system? In any case, he looks more and more worried as the trailer goes on.

THE NOT-SO-FUN FUN FAIR

Look at this cute family, enjoying the Fourth of July fireworks from the top of the Ferris wheel. Now look at the little girl’s face, darkening as if something very bad was about to happen and she wants to go down right now, please. This Independence Day will put Roland Emmerich's to shame.

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MAYOR KLINE, THE PUPPET MASTER?

The biggest clue as to who the secret villain is this season seems to point at Mayor Kline. Not only is his name on top of the Fun Fair that will completely collapse, but the way his hand shoots out as the carousel spins faster and faster points to the idea that he is the circus master, keeping everyone in Hawkins in the same place for some nefarious reason that has nothing to do with securing votes.

The final trailer also shows a masked scientist standing next to the particle collider right before it starts to spin – from the colors to the perspective, it is a perfect mirror scene that might point again at Mayor Kline’s sinister intentions – or maybe just the biggest red herring in the history of untrustworthy trailers.

As a final clue the ominous words that we hear in the trailer just as Mayor Kline’s name disappears from the screen sounds like something a dubiously elected politician (or an evil entity from a parasite dimension) would say to their captive audience: “You let us in. And now, you are going to have to let us stay.”

Created by the Duffer Brothers, Stranger Things stars Winona Ryder, David Harbour, Finn Wolfhard, Millie Bobby Brown, Gaten Matarazzo, Caleb McLaughlin, Noah Schnapp, Natalia Dyer, Charlie Heaton, Joe Keery, Priah Ferguson, Cary Elwes, Jake Busey and Maya Thurman-Hawke. Season 3 arrives July 4 on Netflix.